High-frequency signaling system



n l quency intermediate the two sources andthe current supplied from the two sources is preferably controlled by V ing its speed within will cause a decrease Patented Dec. 7, 1926.

UNITED i STATES ERNST W. ALEXANDEBSON,

HIGH-FREQUENCY SIGNAING oir scisntmoaians, maw Yont ELECTRIC COMPANY, a. consonancia ci? :auf:` l:

Paras application nica april; :aisee amai ne.

My present invention relates to high fre queiicy signaling systems and more particularly to radio transmitting 'systemsof the I multiplex type.

The object ofiny invention is to provide a transmitting system wliereb two sources of high frequency power of diii'erent Afrequem' cies, suoli, for example, as high frequency alternators, may be operated upon a single iu antenna for simultaneously transmiting two distinct and separate signals.

In carryingniy invention into effect I einploy two sources o'f high frequency current di'ering-,sutiiciently in frequency to permit i5 of easily differentiating between the two signais transmitted. This difference in fre quency does not need to be over one per cent. The antenna to which the energy from these two sources is supplied is tuned to a frefrequencies of the means 'of magnetic am liers of the general type described iii my S. Patent, 1,206,643

' No difficult-y will be 'experienced in operatingthealternator whose frequency is lowei than that for which the antenna is tuned as 'this alternator will work on that side of the antenna tuning curve where the current is 30 increasing. If then lthe speed of the alternator tends Ito increase the current supplied to the antenna and the load on the alternators will increase and this `will tend to slow down the alternator and assistin keepthe desired range. For the alternator which works 0n that side of the antenna tuning curve when the current in decreasing, however, an increase in speed in current and the alternator will tend to speed up still more. Because of this characteristic it will be difficult to maintain the speed of the alternator within the narrow range essential for efficient transmission and reception. To overcome this disadvantage I provide in conjunction with tlie second alternator a tuning which is so ar'ran'd and proportioned that the circuit to whic the energy is supplied is tuned for a certain minimum current so that if the speed of the alternator either increases or decreases the current supplied by the alternator will increase. By operating the alternator at or near this point on its tuning curve it will be comparativeliyi'lisy to keep its speed within the desired ts. i

The "novel features which characteristic of my invention ar with particularity in the a" the invention itself, iicweve. organization and method best he understood by lowing description t i connecti the accompanying` in which indicated' diagram which my invei'iticn. A. feet.

As indicated in the rar-rica high frequency alternan i' plying energy to a radiating which is tuned by nieais at the tun' 2. Alternator A, the frequency ci slightly less than the frequency at: which f antenna is tuned, is connected to the ain ,l by; means of the nst'ormer 3,

w ile alternator B, the i l .y or' which is slightly greater than that at which tenna l is timed, is directly connected to the antenna at point l and is shuiited by con-- denser 5. A condenser 6 in series with nator A is i'ovided of suiiieient capacity to Si? neutralize tlie internal reactance oi, the alternator A for the frequency ot i3, and a c denser 7 iii series with alternator B is i, vided with suliicient capacity to neutralize the internal reactance of alternator B 'for the frequency of alternator A.. i stabilizing,f resistance 8 is inserted in. the circuit of alternator B for a 'purpose which will ha more fully explained hereinafter.

In order to control the currents supplied #no from alternators A and B to the antenna magnetic ampliiiers of the type described in my U. S. Patent 1,206,643 having high fre-- quency windings 9 and controlling 4windings lO-are employed. In shunt to each of tie alternators A and B I aise provide a circuit made up of a resista-nce il. and a second netic amplifier l2. The magnetic amplifiers are controlled by means of a key 13 and a source of energy 14 for supplying current to i the controlling windings of the amplifiers. When the key for alternator A is in the po tion shown in the drawing, 'the vcentr ig winding 1 0 will saturate the iron the netie amplifier and permit the current from alternator A to be readily suppiied to fji antenna. When the key i3. is operated to make contact at 15, the controlling current being removed from winding'lti, the'wndings 9 will act as a high impedance from the 3W e ator and practically no current will be supjlied to the antenna. The alternator is magnetic amplifier, however, will by the resistance 1l and the tic amplilier 12 so that the operation hey alternator fr will not affect the ma tuning or resistance in any way in vr the alternator' B is concerned.. The holds true for the operation of alter- B by means of its lrey and magnetic Wipliiier.

rihe operation of the system which I have tescribcd may best be understood by reference to a set ot numerical constants for a to radiating systen'i which may be employed in carrying my invention into ledect. Assume uirst the following: antenna resistance /1() ohms; antenna impedance, 100 ohms; feed ratio, 5; alternator resistance, 3 ohms; alternator voltage3 2300 volts,

it is desired to operate two alternaat wave lengths diering about 1% al" rnator should be about 1/0/5 out of tune with the antenna. This means that the antenna besides having a resistance ot i@ ohms has a reactance impedance of 1 ohm, which appears a capacity with reference the lower frequency' and as an induct- "h reference to the higher frequency. c fcc-d circuit therefore with the feed ted t e antenna will appear figher frequency current a e ot .e 2 ohms in 'series with a rence oit olxns, I

'I us now consider the operation ofthe atc-r l which is assumed to have the :r frequency and consider the opera- 'his alternator from a standpoint .y1 The feed circuit of this alter- Le natur has a series inductive reactance of 25 ohms and a series resistance ot 121/2 ohms. rl'his is cquirclent to a circuit consisting approtimately.l (l ohms inductive reactance in multiple .w ith ohms resistance. 45 The condenser then should have an im pedance about l5 clima ln order to dc- 'terznine this: last value the rule is followed 'y at the energy in the alternator circuit id be at least as great when no energy is supplied to the antenna as when the 'ing the normal amount of Tender these conditions it the alternator should begin to speed up the antenna lo'ad iti/culti decrease because the ant/enna would iecome out ot tune with the alternator. 2f? .herr-:evere the entire. load on the antenna is removed from the alternator and at the e time an equal load is placed on the or circuit it will be safe to assume tuo usual type of speed regulator will e taire care any variations betwo points,

should be given that the power facnomme fore be equivalent lto a resistance of 121/2 ohms in series with a capacity reactance ot 25 ohms.

It the resistance 8 is given a value of about21/5 ohms the total resistance in the circuit of alternator B will be about 51/2'- ohms and the feed circuit of the alternator including internal and external resistance will be equivalent to a resistance of 18 ohms in series with the ca acity reactance of 25 ohms. The combine eiect of these is an impedance of 30.5 ohms to `which the elec.- tromotive force of 2300 volts of the, alternator is applied. The current in the alternator circuit then will be amperes which with a feed ratio oi 5 will give a total antenna current of 375 amperes and the total energy supplied by the alternator will be about 102 kw.

Assume now that the alternator is speeded up shunt condenser ot l5 ohms, which is in series with the internal and external resistance of the alternator which is 51/2 ohms. The impedance of the circuit then will be about 16.6 ohms, and it'will be found that the alternator current will be about 138 amperes. The energy in the alternator circuit -will then be about 107 kw., which is slightly higher than the 102 kw. load which the full amount of energy was being supplied to the antenna. Under these conditions it may be concluded that the circuit described will be sufficiently 'stable to operate with a standard speed regulator. The circuit of the alternator l5 will have practically no dctuning eil'cct upon that ot alternator A as may be seen from the following: The circuit of alternator B consists of a shunt capacity reactance of 15 ohms in multiple with a resistance of 5% ohms. This shunt circuit can be resolved in a series circuit of 41/2 ohms resistance in series with 2 ohms capacity reactance. The whole circuitof alternator B therefore will act practically as a zero impedance through which the `current of alternator A may flow without any detuning eEect on the antenna, The only reactive impedance in this case is 2 ohms capacity reactance whereas it requires 25 ohms resistance to detune the ann tenna one-half of 1%.

The operation of alternator A will have so that the only load on. it -is the .Y

no appreciable detuning eifect upon the antenna so far as alternator B is concerned. The conditions of operation in this case will be the same as described above for alternator B except that the antenna is capacity and the shunt is inductive reactance. In this case, however, it will not be necessary to use a shunt which draws an-idle current because the speed conditions are fundamentally stable. An inductive shunt of 20 to 25 ohms may therefore be suitable and this inductive shunt-may be furnished by the magneti'zing current of the transformer 3, which is employed in order that it may be possibleto operate both alternators at ground potential.

VYhat I claim as new and desire to secure by Letters Patent of the United States;

is :n f

l. A signal transmitting system comprising a resonant transmitting eircuit'and two high frequency alternators connected thereto one having a frequency slightly lower that the resonant frequency of the transmitting circuit and the other having a frequency slightly higher than the resonant" frequency of the transmitting circuit, and1 means connected to the transmitting circuit for insuring stable operation of the second alternator. 1

2. A signal transmitting system comprising a resonant tiansmitting circuit and two high frequency alternators connected. thereto one having a frequency slightly lower than the resonant frequency of the transmitting circuit and the other having a fre-A quency slightly higher than the resonant frequency of the transmitting circuit, the first of said alternators being connected to the transmitting circuit by means of a transformer, and the second of said alternators being connected in shunt to a condenser in the transmitting circuit. v

3. A signal transmitting system comprising a resonant transmitting circuit and two high frequency alternators connected thereto one having a frequency slightly lower than the resonant frequency ofthe transmitting circuit and the other having a frequency slightly higher than the resonant frequency-el the transmitting circuit, the `first ol' sind alternators being connected to the transmitting, circuit by means of a transfrirme". and the second of said alternators being connected in shunt to a 'condenser inthe transmitting circuit, the impedance of said condenser being equal to 'approximately half ,the inductive impedance quency slightly higher than) the resonant frequency oit the transmitting circuit, a capacity in series with the first alternator for neutralizing its internal reactance at the frequency of the second alternator and a capacity in series with the second alternator for neutralizing its internal reactance at the frequency of the first alternator.

i 5. A signal transmitting system comprising a resonant transmitting circuit and two high frequency alternators connected thereto one having a frequency slightly lower than the resonant frequency of the transmitting circuit and the other having a frequency slightly higher than the resonant frequency of the transmitting circuit, magnetic amplifiers in series with both of said alternators rfor controlling the signaling current supplied therefrom, and means for substituting in the transmitting circuit iinpedances quivalent to the alternator impedances when the alternators are not supplying current to the transmitting circuit.

6. A signal transmitting system compris-- ing a resonant transmitting circuit and two high frequency alternators connected thereto one having a frequency slightly lowerthan the resonant frequency of the transmitting circuit and the other having a frequency slightly higher than the resonant frequency of the transmitting circuit, magnetic amplifiers in series with both of said alternators for cont-rolling `the signaling curi-ent supplied therefrom, impedance circuits shunt- 'ing said alternators'and magnetic ampliiiers for controlling the impedances of the shunt circuits, i

In Witness whereof, I have. hereunto set my hand this 8th day of April, 1922.

ERNST r. w. ALnXANiinRsoN.

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